<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <!-- 
    设置item在主轴上的尺寸
    flex-basis:  
          优先级 ：
              max-width/max-height >
                min-width/min-height >
                    flex-basis > width/height
  -->
  <style>
    .container{
      height: 200px;
      border: 1px solid;
      display: flex;
    }
    .container div{
      border: 1px solid;
      background-color: #ccc;
    }
    .container :nth-child(1){
      flex-basis: 100px;
      min-width: 150px;
    }
  </style>
  <div class="container">
    <div>1</div>
    <div>2</div>
    <div>3</div>
  </div>


</body>
</html>